Method and system for gas stunning of poultry for slaughter

ABSTRACT

A method for gas stunning of poultry for slaughter is in which the poultry arrives at the poultry slaughterhouse, for example, in transport crates, where the poultry is subjected to gas after the poultry have been taken out of the transport crates, and where the poultry are conveyed by conveyors ( 18, 20, 24, 32 ) successively through a stunning chamber ( 8 ). The influence of the stunning gas for stunning of the poultry is adjusted in the stunning chamber by reducing or increasing by adjusting an effective length of at least one conveyor in the stunning chamber ( 8 ).

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. Ser. No.10/543,187, filed Jan. 9, 2006, now U.S. Pat. No 7,331,848 and theentire disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a method for gas stunning of poultry.

BACKGROUND OF THE INVENTION

Over time, many different methods have been proposed for gas stunning ofpoultry arriving at the poultry slaughterhouse in transport crates, withno remarkable success. In practice however, several parameters must beconsidered in order to be able to optimize a method for gas stunning ofpoultry for slaughter.

To optimize the method, the following parameters must be considered:

-   -   Conveying speed (capacity of the system).    -   Size and number of birds in the transport crates.    -   The physical condition of the poultry flock which is determined        by continuously observing variations in stress condition or        resistance of the poultry which are significant for determining        the time necessary for stunning the poultry which further may        vary because of conditions in broiler houses, temperatures,        transport time, and waiting time in the slaughterhouse.

To optimize the gas stunning it is furthermore necessary to be able tocontinuously consider all these parameters prior to and during gasstunning of the poultry supplies delivered to the slaughterhouse, andcontinuously apply the most advantageous parameters to achieve optimumgas stunning of the actual chicken flock at any time to be stunned andslaughtered, respectively.

To optimize these parameters, different periods of stunning time can beapplied, but variations in the gas concentration, and variations of gasconcentration in the different sections of the conveying route must alsobe considered, dependent on the conveying route length and conveyingroute location in the stunning chamber.

The gas concentration may be monitored and controlled by means ofsensors having different locations, and a PLC control system. Adjustmentof the stunning time and simultaneous variation of the gas concentrationrequire a change in the previously used methods by which a givenslaughtering capacity of number of birds per minute required a fixedconveying time through stunning chamber. A given rate of slaughtering(slaughtering capacity) will always be determined by other subsequentparameters that cannot be changed right away why they are maintained.Consequently it may furthermore be necessary to be able to change thedegree of stunning, depending on the condition of the poultry uponarrival at the slaughterhouse and unloading for slaughter.

SUMMARY OF THE INVENTION

On this background it is the purpose of the invention to provide animproved method for gas stunning of poultry for slaughter, which methodby means of simple provisions and means makes it possible to optimizethe stunning by being able to allow for all the parameters mentionedabove.

The method according to the invention adjusts the influence of the gasfor stunning of the animals by reducing or prolonging the conveying timeand/or the active conveying route length of the animals on saidconveyors through the stunning chamber. It has surprisingly appearedthat by means of such simple provisions it is possible to optimize thestunning, while at the same time allowing for all the parametersmentioned. As an especially important thing it should be mentioned thatat the same time it is possible to consider the welfare of the animalsby observing the stunning condition of the animals before they reach theactual slaughter. If the stunning condition of the animals is notoptimum, it will be easy to prolong or reduce the conveying time and/orthe conveying route through the stunning chamber.

An optimum condition of stunning will be that the animals are so wellstunned that with certainty they do not awaken before they reachslaughtering. On the other hand it is also important that the animals donot die in stunning because it is important that the pumping function ofthe heart is maintained in order to contribute to the pumping out ofblood when the necks of the animals are cut in the actual slaughter.

Appropriately, by the invention a method is used by which the adjustmentof the conveying time through the stunning chamber is effected byincreasing or reducing the speed of the said conveyors.

By the method according to the invention it may furthermore beadvantageous that the adjustment of the conveying route through thestunning chamber is effected by reducing or prolonging the activeconveyor runs of the respective conveyors.

Furthermore, the method according to the invention may be modified suchthat the influence of the gas for stunning of the animals moreover isadjusted by varying the gas concentration at varying heights in thestunning chamber in that increasing gas concentration is applied in adirection downwards in the stunning chamber

The invention furthermore relates to a system for gas stunning ofpoultry for slaughter comprising a substantially horizontal conveyorarranged for receiving and introducing poultry for slaughter to agas-filled stunning chamber in which a downwards running conveyor isarranged, which conveyor is arranged for successively conveying thepoultry downwards in the stunning chamber, and an upwards runningconveyor arranged for successively conveying the poultry upwards and outof the stunning chamber, wherein the downwards running conveyor eitherhas a conveyor having a downwards running course and a horizontalcourse, the downwards running conveyor, comprising mutually interactingtelescopic members for adjustment of the active conveying route length,or are constituted by a helical conveyor interacting with a horizontal,telescopic conveyor.

Preferably, the system according to the invention is provided such thatthe upwards running conveyor is constituted by conveyors having mutuallyinteracting telescopic members, namely, a horizontal conveyor and anupwards running conveyor having a slanting course.

Appropriately, the system according to the invention is provided suchthat the stunning chamber is divided into a number of horizontal zones,for example, a lower zone having a gas concentration (C0²) ofapproximately 45-51%, an intermediate zone having a gas concentration(C0²) of 25% to approximately 32%-46%, and an upper zone having a gasconcentration (C0²) of 5% to approximately 8%-10%. Sensors are providedwith the upper zone limits for monitoring and control respectively ofthe gas concentration in the zones. The actual gas concentrationpercentage varies a great deal in connection with shift between stoppingand operation, and upon a changed rate of motion of the. This variationin gas concentration has relatively small influence on the stunningresult, whereas the time of presence, especially in the first zone, andthe total time of presence in the stunning chamber have great influence.

The system according to the invention is preferably provided such thatit comprises a PLC control system for controlling a number of mutuallydependent mechanical parameters, for example speed of conveyors, setting(17.6 meters/minute), number of birds (chickens) on conveyors, speed ofslaughtering line, setting (148 birds/minute).

If one setting is changed, the other settings are changedcorrespondingly, for example if the birds are larger, it means thatthere are fewer animals on the conveyors, but the speed of theslaughtering line continues to be the same. Consequently it becomesnecessary to convey more animals per minute through the stunningchamber, that is, increased conveying speed. At the same time eachindividual bird is larger which is why it is stunned for a longer time,is longer conveying time and conveying route length respectively arerequired. through the stunning chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below with reference to thedrawing in which

FIG. 1 shows a longitudinal sectional view, partially in section,through an embodiment of a system for gas stunning of poultry forslaughter according to the invention; and

FIG. 2 shows a top view of another embodiment of a system for gasstunning of poultry for slaughter.

DETAILED DESCRIPTION OF THE INVENTION

The system 2 shown in FIG. 1 for gas stunning of poultry for slaughtercomprises a supply conveyor (not shown) for supply of poultry, which forexample arrives at the slaughterhouse by truck, and which have beentaken out of any transport crates before they arc transferred to thestunning system 2. The poultry 4 is transferred successively to astunning conveyor 6 which actually is a system of endless conveyorshaving a number of sections running downwards into a stunning chamber 8,the major part of which is a concrete pit 10 lowered in relation to thefloor level, which chamber is filled with stunning gas, for example CO2with varying gas concentrations, namely, an upper or first zone 12having a gas concentration of approximately 5% to approximately 8%-10%,an intermediate or second zone 14 having a gas concentration ofapproximately 25% to approximately 32%-46%, and a lower and third zone16 having a gas concentration of approximately 45-51%.

The gas concentration in the zones 12, 14, 16 can be further variedaccording to requirements, for example in relation to bird size or type.The gas concentration in the respective zones is controlled by suitablegas sensors and an actually known gas filling/control system withfilling valves.

From the stunning conveyor 6, the poultry 4 is successively conveyedinto a downwards running conveyor section 18, which continues into ahorizontal conveyor section 20, whose active length can be varied bymeans of a telescopic system 22. From the conveyor section 20 thepoultry 4 is transferred to a downwards running conveyor section 24whose active length can be varied by means of a telescopic system 26which interacts with the telescopic system 22 for the conveyor section20. From the conveyor section 24 the poultry 4, which by now is stunned,is conveyed onto a horizontally running conveyor 28 whose activeconveying route length also can be varied by means of a telescopicsystem 30. The stunned poultry 4 is then conveyed upwards and out fromthe stunning chamber 8 by an upwards running conveyor 32, which, and forbeing able to interact with the conveyor 26, also comprises a telescopicsystem 34 for variation of the active conveying route length of theconveyor 28.

From the conveyor 32 the stunned poultry are transferred to an externalconveyor for being shackled on a slaughtering line. Shortly after thestunned chickens have been shackled by their legs in slaughter shackles,the chickens pass a slaughter location where their necks are cut so thatthe chickens bleed out as a result of the pumping function of theirhearts still being intact if the gas stunning is optimum.

If it is determined that the gas stunning either is too great, that isthe chickens are already dead, the stunning must be adjusted byshortening the conveying route and/or the conveying time through thestunning chamber so that the stunning becomes less. If the chickens onthe contrary show signs of too little stunning, the stunning mustlikewise be adjusted so that the conveying route and/or the conveyingtime through the stunning chamber is increased.

In both situations, adjustment can be effected by reducing or prolongingthe conveying time and/or by changing the active conveying route lengthsof the conveyors 20, 24, 28, 32 by means of the telescopic systems 22,26, 30, 34.

Sensors in given locations ensure that the respective conveyors are incorrect positions, for example for small, medium-sized, or largechickens. An important thing which also influences the stunning resultis that the poultry 4 is stepped downwards, starting in a low gasconcentration of Approximately 5%-10%. The step by step downwardsconveying ensures that the chickens upon starting and stopping lifttheir heads whereby they can freely breathe in the relatively low gasconcentration. This prevents the poultry from becoming stressed, andinjuries are avoided.

To reduce or prolong the conveying time through the stunning chamber 8,it is of course also possible to adjust the speed of the respectiveconveyors.

After the first part of the downwards movement, the poultry has “fallenasleep” and this continues further down where the gas concentration ismax. 50% at the bottom of the chamber. Hereby it is ensured that thechickens will not wake up before their necks have been cut and they havebled out. Furthermore, regarding safety, it is an advantage to lower thestunning chamber below the floor level so that gas leakage above heightof the head an operator is avoided.

The system 36 outlined in FIG. 2 comprises a stunning chamber 38 whichlike the system 2 (FIG. I) described above comprises a concrete pit 40lowered in relation to floor level. After unloading, poultry istransferred to the stunning chamber 38 via a horizontal supply conveyor42 delivering the birds to a downwards running helical conveyor 44 whichat the bottom of the stunning chamber 38 again delivers the now stunnedbirds to a horizontal, telescopic conveyor 46 from which the stunnedbirds are transferred to an upwards running conveyor 48 which conveysthe stunned birds upwards and out of the stunning chamber 38 for furtherconveyance to shackling on a slaughtering line, etc.

The conveyors 42, 44, 46 have relatively large widths of for exampleApproximately 800 mm each, that is at a given speed, the capacity ofthese conveyors is large. In a simple manner the width of the conveyors42, 44, 46 and thus their capacity can be reduced by means of laterallydisplaceable walls 43, 45, 47. By this lateral displacement of the walls43, 45, 47 the conveying route length is moreover varied in that thelength of the helical conveyor is prolonged by forcing the poultryoutwards in the curve and oppositely, by forcing the poultry inwards inthe curve.

Alternatively, the capacity of the cooperating conveyors 42, 44, 46 canbe varied by varying the conveying speed or the conveying route lengthin that the number of “twists” of the helical conveyor 44 can beadjusted to the actual conveying need, just as the active length of thetelescopic conveyor 46 can be varied. In this connection, it should bementioned that the slanting position of the upwards running conveyoralso can be adjusted. The upwards running conveyor is provided withtransversely positioned carriers 50 which, if the conveyor 48 has a verysteep course, can be replaced by cups so that the stunned birds willsurely be conveyed upwards and out of the stunning chamber 38.

1. A method for stunning poultry for slaughter with a stunning gascomprising: conveying the poultry successively through a stunningchamber, wherein an influence of the stunning gas of the poultry isadjusted by increasing or reducing an active length of at least oneconveyor conveying the poultry within the stunning chamber.
 2. A methodaccording to claim 1 wherein the influence of the stunning gas isadjusted by increasing or reducing a time of conveying the poultryexposed to the stunning gas within the stunning chamber.
 3. A methodaccording to claim 2, wherein the increasing or reducing the time ofconveying the poultry through the stunning chamber includes increasingor reducing a speed of the at least one conveyor conveying the poultrythrough the stunning chamber.
 4. A method according to claim 1, whereinthe influence of the stunning gas is also adjusted by varying aconcentration of the stunning gas at varying levels within the stunningchamber through which the at least one conveyor moves with the stunninggas concentration increasing in a downwards direction of movement of thepoultry along the at least one conveyor in the stunning chamber.
 5. Amethod according to claim 2, wherein the influence of the stunning gasis also adjusted by varying a concentration of the stunning gas atvarying levels within the stunning chamber through which the at leastone conveyor moves with the stunning gas concentration increasing in adownwards direction of movement of the poultry along the at least oneconveyor in the stunning chamber.
 6. A method according to claim 3,wherein the influence of the stunning gas is also adjusted by varying aconcentration of the stunning gas at varying levels within the stunningchamber through which the at least one conveyor moves with the stunninggas concentration increasing in a downwards direction of movement of thepoultry along the at least one conveyor in the stunning chamber.
 7. Asystem for stunning of poultry for slaughter with a stunning gascomprising at least one conveyor for receiving and introducing poultryfor slaughtering to, through and out of a stunning chamber containingthe stunning gas in which at least one downwards running conveyor and atleast one upwards running conveyor is disposed for conveying the poultrythrough the stunning chamber, the at least one downwards runningconveyor successively conveying the poultry downwards in the stunningchamber, and the at least one upwards running conveyor successivelyconveying the poultry upwards with the stunning chamber, wherein the atleast one downwards and the at least one upwards running conveyorproviding adjustment of an active length of conveying the poultry withinthe stunning chamber to vary an influence of the stunning gas on thepoultry while within the stunning chamber.
 8. A system in accordancewith claim 7, wherein: the at least one of the downwards runningconveyor includes a downwards running course and the at least oneupwards running conveyor includes an upwards running course which adjustthe active length of conveying of the poultry through the stunningchamber.
 9. A system in accordance with claim 7 comprising: at least onehorizontal conveyor including a horizontal course providing adjustmentof the active length of conveying the poultry through the stunningchamber.
 10. A system in accordance with claim 8 comprising: at leastone horizontal conveyor including a horizontal course providingadjustment of the active length of conveying the poultry through thestunning chamber.
 11. A system in accordance with claim 9 comprising: Atleast one horizontal conveyor including a horizontal course providingadjustment of the active length of conveying the poultry through thestunning chamber.
 12. A system in accordance with claim 7 wherein: theat least one of the downwards running conveyor and the upwards runningconveyor comprises a helical conveyor interacting with at least onehorizontal conveyor to provide the poultry to the stunning chamber andto output the poultry from the stunning chamber.
 13. A system accordingto claim 7, wherein the downwards and the upwards running conveyorscomprise mutually interacting members which telescope to vary the activelength.
 14. A system according to claim 8, wherein the downwards and theupwards running conveyors comprise mutually interacting members whichtelescope to vary the active length.
 15. A system according to claim 8,wherein the downwards and the upwards running conveyors comprisemutually interacting members which telescope to vary the active length.16. A system according to claim 10, wherein the downwards, horizontaland upwards running courses comprise mutually interacting members whichtelescope to vary the actual length.
 17. A system according to claim 7,wherein the stunning chamber is divided into zones which, duringstunning, comprise a lower zone having a stunning gas concentration ofapproximately between 45% and 51%, an intermediate zone having astunning gas concentration of between 25% and approximately 32% to 46%,and an upper zone having a stunning gas concentration of between 5% andapproximately 8% to 10%, with sensors being provided for monitoring andcontrolling of the gas concentration in the zones.
 18. A systemaccording to claim 8, wherein the stunning chamber is divided into zoneswhich, during stunning, comprise a lower zone having a stunning gasconcentration of approximately between 45% and 51%, an intermediate zonehaving a stunning gas concentration of between 25% and approximately 32%to 46%, and an upper zone having a stunning gas concentration of between5% and approximately 8% to 10%, with sensors being provided formonitoring and control of the gas concentration in the zones.
 19. Asystem according to claim 9, wherein the stunning chamber is dividedinto zones which, during stunning, comprise a lower zone having astunning gas concentration of approximately between 45% and 51%, anintermediate zone having a stunning gas concentration of between 25% andapproximately 32% to 46%, and an upper zone having a stunning gasconcentration of between 5% and approximately 8% to 10%, with sensorsbeing provided for monitoring and control of the gas concentration inthe zones.
 20. A system according to claim 10, wherein the stunningchamber is divided into zones which, during stunning, comprise a lowerzone having a stunning gas concentration of approximately between 45%and 51%, an intermediate zone having a stunning gas concentration ofbetween 25% and approximately 32% to 46%, and an upper zone having astunning gas concentration of between 5% and approximately 8% to 10%,with sensors being provided for monitoring and control of the gasconcentration in the zones.
 21. A system according to claim 12, whereinthat the stunning chamber is divided into zones which, during stunning,comprise a lower zone having a stunning gas concentration ofapproximately between 45% and 51%, an intermediate zone having astunning gas concentration of between 25% and approximately 32% to 46%,and an upper zone having a stunning gas concentration of between 5% andapproximately 8% to 10%, with sensors being provided for monitoring andcontrol of the gas concentration in the zones.
 22. A system according toclaim 13, wherein that the stunning chamber is divided into zones which,during stunning, comprise a lower zone having a stunning gasconcentration of approximately between 45% and 51%, an intermediate zonehaving a stunning gas concentration of between 25% and approximately 32%to 46%, and an upper zone having a stunning gas concentration of between5% and approximately 8% to 10%, with sensors being provided formonitoring and control of the gas concentration in the zones.
 23. Asystem according to claim 14, wherein that the stunning chamber isdivided into zones which, during stunning, comprise a lower zone havinga stunning gas concentration of approximately between 45% and 51%, anintermediate zone having a stunning gas concentration of between 25% andapproximately 32% to 46%, and an upper zone having a stunning gasconcentration of between 5% and approximately 8% to 10%, with sensorsbeing provided for monitoring and control of the gas concentration inthe zones.
 24. A system according to claim 15, wherein that the stunningchamber is divided into zones which, during stunning, comprise a lowerzone having a stunning gas concentration of approximately between 45%and 51%, an intermediate zone having a stunning gas concentration ofbetween 25% and approximately 32% to 46%, and an upper zone having astunning gas concentration of between 5% and approximately 8% to 10%,with sensors being provided for monitoring and control of the gasconcentration in the zones.
 25. A system according to claim 10comprising a PLC control system for controlling mutually dependentmechanical parameters including a speed of the at least one conveyorsand speed of a slaughtering line which receives birds which have beenstunned in the stunning chamber.